Voltage is the amount of pressure in a power source. It is what pushes your current through the system. It is measured in volts, also marked as V. It was also once called electromotive force or EMF, which is why you sometimes see voltage represented as E.
Voltage can also be read as the difference in electric potential between two described points. An easy way to think about it is the amount of water in a hose. The more pressure [or voltage] there is, the more water there will be and the faster the water will come out.
Voltage is used to determine when loads and power sources are operating as they should. If voltages don’t match the standard, it is an easy way to tell that something might be wrong.
Understanding voltage can be important when setting up solar panels. Depending on how you wire up your solar panels together, you have the potential to increase the voltage [when arranged together in series], or current [when arranged up in parallel].
Increasing voltage in a system can increase efficiency. This is ideal if you have to send power over a long distance because it experiences less energy loss.
There are two main different kinds of voltages, which are AC and DC. There are some key differences between them including how they work, what they are used for, and where you are likely to find these kinds of power sources.
DC power stands for direct current, which means that the current is running in one direction. (1) DC currents are used most often with products that don’t need a lot of power.
Some common examples are power tools and chargers in cars. (2) There are also DC generators, batteries, and converters. Solar panels are DC power as well. This is why you often need an inverter to convert that DC power into something more stable or more useful in your home, such as AC power.
DC power has some advantages. DC power can be more efficient, especially when shorter wires between the device and its power source are involved. Plus, because the voltages are usually far lower than AC power, there isn’t as much of a health risk if you get shocked.
However, there are disadvantages of DC power as well. For one, they usually need bigger cables, fuses, switches, and more. It is also pretty hard to find appliances that run on DC power, and there are higher chances of fire hazards when the wires aren’t installed correctly.
DC is used a lot in vehicles, and electronics. However, most of the time, there are converters either in the power supply or in the electronic device to allow them to run on AC power since that is more universally accepted.
Some common DC voltages are:
AC stands for alternating current. (3) Instead of power flowing in one direction, it changes direction frequently. Because of this, the voltage in AC circuits also reverses as the currents change direction.
Many homes run on AC power, so anything you have that uses DC power needs to have some sort of converter. While DC power can be better for electronics and appliances, AC power is better when sent over long distances.
Because of the way power grids are set up, AC power is the better opinion because you only need a transformer to convert voltage levels and it can go long distances without degrading too much.
Some common AC voltages used are:
Of these voltages, 120 and 240 are the most common and the ones you will find in homes all around the world. 110V, 115V, and 220V tend to be more for appliances and motors. Voltages like 125, 130, 230, and 250 are for items like switches, lightbulbs, and outlets. (4)
The different voltage numbers are used to describe the amount of potential energy there is to move around. Generally, when you are connecting something to your system, it isn’t a good idea to go over the maximum voltage allowed.
Since solar panels use DC power, you have to make sure you don’t go over the maximum voltage of your inverter and battery system. Generally, in the United States, you want to stay around 600V and 1000V, depending on your systems.
It is always a good idea to learn, at a minimum, what the normal voltage level of your system should be. That way, you can easily catch when something is wrong. If your voltage levels are higher or lower than normal, it may be a sign something is wrong in your system and isn’t working as it should.
While a bit of fluctuation throughout the day is normal, when the voltage changes dramatically for a long period of time, it is showing that something isn’t doing the job it should be.
Voltage can fluctuate due to the amount of sunlight on your solar panels and the total temperature of your system.
For traditional rooftop solar panels, you typically want between 20 and 40 volts. This is the low voltage for DC power. However, depending on the specific type of panel, you may get slightly different voltage levels. This is one of the reasons you typically want to stay with the same kinds of solar panels, so you get the same voltage.
Most RVs and vehicles run off of DC power anyway. So for most items in your RV or van, you just need a typical 12V system. However, an inverter may be needed for objects like a microwave and AC.
Commercial and industrial applications vary. You can see AC uses around 240, 480, and 600 volts pretty frequently. In the US, 120V or 208V is still the most common, even for commercial buildings, but for industrial, the number often increases to better benefit big appliances. (5)
- Storr, W. (2022, October 27). DC Circuit Theory. Basic Electronics Tutorials. https://www.electronics-tutorials.ws/dccircuits/dcp_1.html
- Carnegie Mellon University. (n.d.). AC/DC: The Push for Better Home Energy Efficiency – Engineering and Public Policy – College of Engineering – Carnegie Mellon University. https://www.cmu.edu/epp/news/2016/acdc-the-push-for-better-home-energy-efficiency.html
- Kuphaldt, T. R. (2021, January 26). What is Alternating Current (AC)? Basic AC Theory | Electronics Textbook. https://www.allaboutcircuits.com/textbook/alternating-current/chpt-1/what-is-alternating-current-ac/
- Electrical Voltages – Electrical 101. (n.d.). https://www.electrical101.com/electrical-voltages.html
- Electrical Service Types and Voltages – Continental Control Systems, LLC. (2021, January 18). Continental Control Systems, LLC. https://ctlsys.com/support/electrical_service_types_and_voltages/